Capillary electrophoretic separation

An exeuaple of a nodular apparatus for capillary electrophoretic separation methods, is shown in Figure 4.43 [637-639,681-684]. It Offers a choice of automated sample introduction methods with on-column detection and has a... 

Capillary electrophoretic separations are performed in small diameter tubes, made of Teflon, polyethylene, and other materials. The most frequently used material is fused silica. Fused silica capillaries are relatively inexpensive and are available in different internal and external diameters. An important advantage of a fused silica capillary is that the inner surface can be modified easily by either chemical or physical means. The chemistry of the silica surface is well established due to the popularity of silica surfaces in gas chromatography (GC) and liquid chromatography (LC). In capillary electrophoresis, the silica surface is responsible for the EOF. Using surface modification techniques, the zeta potential and correspondingly the EOF can be varied or eliminated. Column fabrication has been done on microchips.13... 

Figure 16 Capillary electrophoretic separations of r-HuEPO at 1 mg/ml in 50 cm x 75 p i.d. uncoated capillary at 10 kV. Buffers used were (A) 10 mM tricine/10 mM NaCl, pH 6.2 (B) 10 mM tricine/10 mM NaCl/2.5 mM 1,4-diaminobutane, pH 6.2 and (C) 10 mM tricine/10 mM NaCl/2.5 l,4-DAB/7M urea, pH 6.2. (From Watson, E. and Yao, F., Anal. Biochem., 210, 389, 1993. With permission.)...

Towns, J. K. and Regnier, F. E., Capillary electrophoretic separations of proteins using nonionic surfactant coatings, Anal. Chem., 63, 1126, 1991. 

Rundlett, K. L. and Armstrong, D. W., Effect of micelles and mixed micelles on efficiency and selectivity of antibiotic-based capillary electrophoretic separations, Anal. Chem., 67, 2088, 1995. 

Rawjee, Y. Y and Vigh, Gy., A peak resolution model for the capillary electrophoretic separation of the enantiomers of weak acids with hydroxypropyl (3-cyclodextrm-containing background electrolytes, Anal. Chem., 66, 619, 1994. 

Watson, E. and Yao, F., Capillary electrophoretic separation of human recombinant erythropoietin (r-HuEPO) glycoforms, Anal. Biochem., 210, 389, 1993. 

In E. Coli bacterial lysates, the proteome (i.e., the full array of proteins produced) was analyzed by isoelectric focusing and mass spectrometry.97 A comparison of capillary electrophoretic separation and slab gel separation of a recombinant monoclonal antibody demonstrated that the precision, robustness, speed, and ease-of-use of CE were superior.98 Seventy-five proteins from the yeast ribosome were analyzed and identified by capillary electrophoresis coupled with MS/MS tandem mass spectrometry.99 Heavy-chain C-terminal variants of the anti-tumor necrosis factor antibody DE7 have been separated on capillary isoelectric focusing.100 Isoforms differing by about 0.1 pi units represented antibodies with 0,1 or 2 C-terminal lysines. 

Hj erten (1983) reported the use of crosslinked polyacrylamide gels for the capillary electrophoretic separation of proteins. However, crosslinked polymers are quite rigid, and the capillary has a short lifetime. 

Nishi et al. [110] used dextran and dextrin as chiral selectors in capillary-zone electrophoresis. Polysaccharides such as dextrins, which are mixtures of linear a-(l,4)-linked D-glucose polymers, and dextrans, which are polymers of D-glucose units linked predominantly by a-(l,6) bonds, have been employed as chiral selectors in the capillary electrophoretic separation of enantiomers. Because these polymers are electrically neutral, the method is applicable to ionic compounds. The enantiomers of basic or cationic drugs such as primaquine were successfully separated under acidic conditions. The effects of molecular mass and polysaccharide concentration on enantioselectivity were investigated. 

Obviously, the main purpose for the introduction of CL detection coupled to CE separations is inherent to the development and improvement of sensitive and uncomplicated devices to achieve a decrease of the band broadening caused by turbulence at the column end, together with the attractive separation efficiency of CE setups. With this purpose in mind, Zhao et al. [83] designed a postcolumn reactor for CL detection in the capillary electrophoretic separation of isoluminol thiocarbamyl derivatives of amino acids, because, like other isothiocyanates, isoluminol isothiocyanate has potential applications in the protein-sequencing area. 

A recent trend in analytical chemistry involves the application of CL as a detection system in combination with capillary electrophoresis as prior separation methodology, providing excellent analytical sensitivity and selectivity and allowing the resolution and quantification of various analytes in relatively complex mixtures. Until the 1990s, chemiluminometric detection was not applied after capillary electrophoretic separation, but fast developments from some im-... 

Several modes of capillary electrophoretic separation are available ordinary CE, capillary zone electrophoresis, capillary electrokinetic chromatography, capillary gel electrophoresis, capillary electrochromatography, capillary isota-chophoresis, and capillary isoelectric focusing. The different separation mechanisms make it possible to separate a wide variety of substances depending on their mass, charge, and chemical nature.53... 

The effect that the quality of the bed structure has on the chromatographic properties of columns packed with particles has been well known for a long time [1]. Similarly, the efficiency of capillary electrophoretic separations reaches its maximum for a specific capillary diameter, and then decreases steeply for both larger and smaller size [ 117]. Therefore, any improvement in the efficiency of the polymeric monolithic columns for the isocratic separations of small molecules is likely to be achieved through the optimization of their porous structure rather than their chemistry. 

Rawjee, YY, Williams, R.L., Buckingham, L.A., Vigh, G Effects of pH and hydroxypropyl fS-cyclodextrin concentration on peak resolution in the capillary electrophoretic separation of the enantiomers of weak bases. J. Chromatogr. 1994, 688, 273-282. 

In the section General Principles, a comprehensive description is given of the basic principles of the capillary electrophoretic separation process. The concepts of electrophoretic mobility and electroosmotic mobility as well as band dispersion phenomena and resolution are described, using the equations listed in Table 3. A remarkable difference exists between the equations in both chapters in which the electroosmotic velocity and/or the electroosmotic mobility is used. In the Ph.Eur., the terms 4-feo and 4-/teo are used, whereas in the USP the terms feo and Pco are used in the corresponding equations, with the sentence added The sum or the difference between the two velocities (v p and v o) is used depending on whether the mobilities act in the same or opposite directions. ... 

JB Vincent, G Vigh. Nonaqueous capillary electrophoretic separation of enantiomers using the single isomer heptakis(2,3-diacetyl-6-sulfato)-cyclodex-trin as chiral-resolving agent. J Chromatogr A 816 233—241, 1998. 

GM Beck, SH Neau. Optimization of A-carrageenan as chiral selector in capillary electrophoretic separations. Chirality 12 614-620, 2000. 

Watarai, H., Takahashi, I. (1998). Comparison of three different microemulsion systems as the run buffer for the capillary electrophoretic separation. Anal. Commun. 35 289—292. 

CL Cooper, JB Davis, MJ Sepaniak. Mechanisms of enantiomeric resolution in cyclodextrin-modified capillary electrophoretic separations of binaphthyl compounds. Chirality 7 401-408, 1995. 

Capillary Electrophoretic Separations of Drugs. A.S. Cohen, S. Terabe and Z. Deyl. Elsevier, Amsterdam (1996). 

Okada, T., Non-aqueous capillary electrophoretic separation of Bronsted acids as heteroconjugated anions, /. Chromatogr. A, 771, 275-284,1997. 

Markuszewski, M. J., Stepnowski, R, and Marszall, R, Capillary electrophoretic separation of cationic constituents of imidazolium ionic liquids, Electrophoresis, 25, 3450-3454, 2004. 

E. Watson and F. Yao, Capillary electrophoretic separation of recombinant granulocyte-colony stimulating factor glycoforms, J. Chromatogr., 650 442(1993). 

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